The invention relates to machine elements and mechanisms, but more particularly, the invention relates to V-block belts.
V-block belts are extensively used as variable speed belts because their construction allows a low thickness to width ratio to accomodate desirable speed ratios changes in variable speed belt drives. Such belts are usually constructed with a flat band type load carrying member that establishes an equatorial plane about which bending takes place. V-blocks are longitudinally spaced and attached to the load carrying member such as by clamping or molding. Examples of clamped-type belts appear in U.S. Pat. Nos. 1,446,018; 2,343,367 and 2,647,410. U.S. Pat. No. 4,177,687 teaches how to solve many horsepower/torque problems of clamped-type V-block belt by using a molded polymeric material around diagonal side members of a reinforcement that surrounds and supports the load carrying member.
Block belts may be extremely flexible in torsional bending because of the thinness of the flat load carrying member spanning successive blocks. Lack of torsional rigidity may allow the V-blocks to cock as they enter a pulley which may introduce or aggravate belt vibration between pulleys. U.S. Pat. No. 1,446,018 teaches how to inhibit belt back bending in one direction of belt travel with successive plates that each extends from the top of one V-block and tangentially over the load carrying member portion between successive blocks. While such a construction may also add some degree of torsional stability to a block belt, the system is only partially operative because there can only be an increase in the belt torsional stiffness when the plates are in tangential contact with the load carrying member. Torsional rigidity is decreased as the plates move away from the load carrying member as when the blocks enter a pulley or in free span vibration between pulleys.